I'm a big fan of this dress from Yuki Araki's "Basiques pour petites filles". I have already sewn a version of it, that you can look at here. I like its soberness - I am not much into frills.
This is a second version of this dress, more summery, very fresh. The fabric is cotton from Fabrics Galore, a great fabric shop between Battersea and Clapham.